1. Field of the Invention
The present invention is generally directed to a bone conduction device, and more particularly, to a piercing conducted bone conduction device.
2. Related Art
Hearing loss, which may be due to many different causes, is generally of two types, conductive or sensorineural. In many people who are profoundly deaf, the reason for their deafness is sensorineural hearing loss. This type of hearing loss is due to absence, destruction, or damage to the hairs that transduce acoustic signals into nerve impulses in the cochlea. Various prosthetic hearing implants have been developed to provide individuals who suffer from sensorineural hearing loss with the ability to perceive sound. One type of prosthetic implant, referred to as a cochlear implant, uses an electrode array implanted in the cochlea. More specifically, an electrical stimulus is provided via the electrode array directly to the cochlea nerve, thereby inducing a hearing sensation in the implant recipient.
Conductive hearing loss occurs when the normal mechanical pathways, which conduct sound to hairs in the cochlea, are impeded. This problem may arise from damage to the ossicular chain to ear canal. However, individuals who suffer from conductive hearing loss frequently still have some form of residual hearing because the hairs in the cochlea are often undamaged. For this reason, individuals who suffer from conductive hearing loss are typically not candidates for a cochlear implant, because insertion of the electrode array into a cochlea results in the severe damage or destruction of the most of the hairs within the cochlea.
Sufferers of conductive hearing loss typically receive an acoustic hearing aid. Hearing aids receive ambient sound in the outer ear, amplify the sound, and direct the amplified sound into the ear canal. The amplified sound reaches the cochlea and causes motion of the cochlea fluid, thereby stimulating the hairs in the cochlea.
Unfortunately, hearing aids do not benefit all individuals who suffer from conductive hearing loss. For example, some individuals are prone to chronic inflammation or infection of the ear canal and cannot wear hearing aids. Other individuals have malformed or absent outer ear and/or ear canals as a result of a birth defect, or as a result of common medical conditions such as Treacher Collins syndrome or Microtia. Hearing aids are also typically unsuitable for individuals who suffer from single-sided deafness (i.e., total hearing loss only in one ear) or individuals who suffer from mixed hearing losses (i.e., combinations of sensorineural and conductive hearing loss). In addition to hearing aids which amplify and direct the amplified sound into the ear canal, some patients received implanted hearing aids or hearing prosthesis which have one or more components implanted in the recipient's skull or between the skull and tissue. However, some recipients are not suited for implanted hearing aids, due to the size, shape and particular condition of the recipient or their skull. In other cases, recipients are not desirous of implanted hearing aids, given their often bulky size or other factors.
Those individuals who cannot benefit from hearing aids or implanted hearing devices may benefit from hearing prostheses that are put into contact with, but not implanted or embedded within or between, the skull bone and the recipient's skin. Such hearing prostheses direct vibrations into the bone, so that the vibrations are conducted into the cochlea and result in stimulation of the hairs in the cochlea. This type of prosthesis is typically referred to as a bone conduction device.
Bone conduction devices function by converting a received sound into a mechanical vibration representative of the received sound. This vibration is then transferred to the bone structure of the skull, causing vibration of the recipient's skull and serves to stimulate the cochlea hairs, thereby inducing a hearing sensation in the recipient.